An inspection of the electrical properties of a semiconductor integrated circuit and the like is carried out by bringing probe pins into contact with a large number of electrode pads of the semiconductor integrated circuit and the like. Constituent materials for probe pins are required to have hardness for ensuring wear resistance against inspection which is repeatedly carried out millions of times, oxidation resistance for suppressing the contamination of objects to be inspected by the formation of oxide films, and other properties, such as low specific resistance for improving signal delays. Examples of conventional materials for probe pins include materials in which beryllium-copper (Be—Cu), phosphor bronze (Cu—Sn—P) and tungsten (W) are used, and materials in which alloys obtained by adding silver (Ag) to palladium (Pd) are used.
Patent Document 1: JP Patent Application Laid-Open No. 10-038922
Patent Document 2: JP Patent Application Laid-Open No. 05-154719
Patent Document 3: JP Patent Application Laid-Open No. 2004-093355
The above-described conventional materials do not provide all of the required properties. That is, copper alloys and tungsten are materials which are oxidized relatively easily although their mechanical properties are sufficient. On the other hand, palladium alloys are somewhat inferior in hardness and the like although they have good oxidation resistance.
Hence, iridium is attracting attention as a new constituent material for probe pins. Since iridium is a metal excellent in oxidation resistance, electrical properties and current resistance and is also adequate in terms of hardness, this metal is suitable as a material for probe pins which are subjected to repeated contact.